Help defining commands

[Guy Shaviv]

I'm trying to typeset music for classical guitar for which I need to be able to 
produce the barre 
symbol. I've managed to acheive the desired output with text spanners via the 
code:

\property Voice.TextSpanner \set #'edge-text = #'("C II " . "")
\property Voice.TextSpanner \set #'direction = #1
\property Voice.TextSpanner \set #'style = #'line
\property Voice.TextSpanner \set #'edge-height = #'(0 . 0.5)
\property Voice.TextSpanner \set #'padding = #1
\property Voice.TextSpanner \set #'enclose-bounds = ##t

c''\startTextSpan ..... \stopTextSpan

I'de like to define this as a pair of commands. The first would be \statBarre 
which would take as 
a parameter the barre position, say \startBarre "IV". The position has to be 
concatinated with the 
"C" symbol and replaced as the first parameter in the edge-text property. The 
second command 
is a simple \stopBarre which I think I can do by just defining:

stopBarre = \stopTextSpan.

Thanks. 

--
Guy Shaviv
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